Method of removing a guide line from a guide post at an underwater well site

ABSTRACT

COUPLING DEVICES USEFUL IN OFFSHORE WELL WORK FOR CONNECTING A GUIDE LINE TO A GUIDE POST, WHICH COUPLING DEVICES INCORPORATE MEANS ALLOWING FOR SEPARATION OF THE GUIDE LINE FROM THE GUIDE POST WHEN THE LATERAL FORCE   APPLIED ON THE GUIDE POST BY THE GUIDE LINE EXCEEDS A PREDETERMINED AMOUNT.

Jan. 12, 1971 w. R. POSTLEWAITE U 3,553,821 METHOD OF REMOVING A GUIDE LINE FROM AGUIDE POST AT AN UNDER-WATER WELL SITE Original Filed May 2, 1966 4 Sheets-Sheet 1 INVENTOR WILLIAM R. POSTLEWA/TE ATTORNEY 05 I 3,553,821 A GUIDE LINE FROM A GUIDE POST AT AN UNDERWATER WELL SITE Originalv Filed May 2, 1966 "Jan. 12, 19.71"

- METHOD OF REMOVING 4 Sheets-Sheet 2' INVENTOR WILLIAM R POSTLEWA/TE BY ATT6ZNEYSZ Janpl2', 1971 w. R. POSTLEWAITE 3,553,821

METHOD OF REMOVING A GUIDE LINE FROM A GUIDE POST AT AN UNDERWATER WELL SITE Original" Filed May 2, 1966 4 Sheets-Sheet 5 F'IG.7

INVENTOR W/LL/AMR POSTLEWA/TE o NIYS 4 151,512; 1911," wiaiaa fl'amnz mm-s21 METHOD OF REMOVING A GUIDE LINE FROM A GUIDE POST AT AN UNDERWATER WELL SITE Original Filed May 2, 1966 4 Sheets-Sheet 4 mvau'r'on WILLIAM R. POSTLEWA/TE BY A -1'0 49 United States Patent 3,553,821 METHOD OF REMOVING A GUIDE LINE FROM A GUIDE POST AT AN UNDERWATER WELL SITE William R. Postlewaite, Menlo Park, Calif., assignor to Chevron Research Company, San Francisco, Calif., a corporation of Delaware Original application May 2, 1966, Ser. No. 546,821, now Patent No. 3,451,699, dated June 24, 1969. Divided and this application Sept. 25, 1968, Ser. No. 795,749

Int. Cl. B23p 19/02 US. Cl. 29-427 1 Claim ABSTRACT OF THE DISCLOSURE Coupling devices useful in offshore well work for connecting a guide line to a guide post, which coupling devices incorporate means allowing for separation of the guide line from the guide post when the lateral force applied on the guide post by the guide line exceeds a predetermined amount.

This application is a division of copending application Ser. No. 546,821, filed May 2, 1966, now Pat. No. 3,451,- 699, granted June 24, 1969, for Coupling Devices For Use In Olfshore Well Work.

This invention relates to coupling means for connecting guide lines to underwater guide posts; and, more particularly, this invention relates to coupling devices useful to connect guide lines to guide posts, which devices include means for limiting the lateral load that can be exerted on the guide posts.

In deep water well drilling and well completion, it is now customary to install guide posts around a well. The tall guide posts stand upright and are used to guide heavy equipment to a precise location at the well site. The guide posts are relatively rigid and are usually from to 20 feet or more in height. Guide cables are connected to the upper ends of the guide posts and extend to a surface vessel or the like. The guide cables are used to guide apparatus from the ship to the guide posts. If the surface vessel moves from a position substantially above the well site, an excessive lateral strain can be put on the posts. If the guide posts are bent or otherwise damaged by the lateral force, it may mean loss of the well since it may not be possible to get equipment back on the well.

It is, therefor, a particular object of this invention to provide coupling means for connecting a guide line to a guide post, which coupling means includes load-limiting means for limiting the lateral load on a guide post to an acceptable safe level.

In a broad aspect, the present invention provides apparatus for use underwater comprising a guide post having an upper end, a guide cable and coupling means for coupling said guide cable to the end of said guide post, said coupling means including means for limiting the lateral force that can be applied to said guide post by said guide cable.

Further objects and advantages of the present invention will become apparent from the following detailed description read in light of the accompanying drawings which are a part of this specification, and in which:

FIG. 1 illustrates, in side elevation with parts broken away for clarity, apparatus assembled in accordance with this invention;

FIG. 1A is a schematic view of a portion of the apparatus of the invention and illustrates the forces acting on the coupling member;

FIG. 2 is an elevational view, partially in section, illustrating the preferred embodiment of the present invention;

FIG. 3 is an enlarged sectional view of a portion of the apparatus illustrated in FIG. 2 and more clearly shows features of the present invention;

FIG. 4 is section 4-4 of H62;

FIG. 5 is section 5-5 of FIG. 2;

FIG. 6 illustrates, in side elevation with parts broken away for clarity, an alternative embodiment of the present invention;

FIG. 7 is a sectional view taken at line 7-7 of FIG. 6;

FIG. 8 illustrates, in side elevation with parts broken away for clarity, still another alternative embodiment of the present invention;

FIG. 9 is a sectional view taken at line 9-9 of FIG. 8; and

FIG. 10 is a sectional view taken at line 10-10 of FIG. 8.

Referring to the drawings and particularly to FIG. 1, there is illustrated an offshore drilling vessel, generally designated by the numeral 30, which has been anchored by lines 432 and 433 over a body of water 33 in approximate vertical relationship over the site where a well has been drilled in the underwater bottom 34. The drilling vessel 30 has an operational base, which is generally indicated by the numeral 300. The operational base 300 of the vessel 30 is suitably maintained to run drill pipe, handle cables, and to perform other functions that are well known in the underwater drilling and well completion art. A permanent base, generally designated by the numeral 36, is located at the subsea well site and forms part of the fixed well site apparatus. The permanent base in this instance includes a pair of guide posts 452 and 453. Flexible guide lines 455 and 456 are connected between the operational base 300 of the vessel 30 and the upper ends of guide posts 452 and 453, respectively.

The guide posts 452 and 453 are tall, rigid posts useful to guide apparatus to specific locations on the well control apparatus. If the drilling vessel for some reason, such as a storm, moves off from over the well site with the guide cables still attached, the cables could come to a position indicated in phantom in FIG. 1. The guide cables are necessarily strong, steel ropes. Therefor, the potential force which would be exerted on the guide posts by the drilling vessel is very large; i.e., being on the order of 40,000 to 50,000 pounds. If even a substantial portion of such a force is applied laterally on the guide posts, bending of the posts can result. If such bending occurs, it may not be possible to come back onto the well. Attempts to straighten or to replace the posts are costly and not necessarily successful, and loss of the well could result. For this reason, coupling devices 40 and 50 are provided to connect the guide cables to the guide posts, which devices limit the lateral pull that can be applied to the posts by the guide cables.

In accordance with the invention then, the coupling device automatically limits the maximum horizontal load component that an inclined guide cable can exert on a guide post. A breaking link is incorporated into the coupling device, which breaking link has a tensile strength of 'less than the tensile strength of the guide line. In normal operating conditions, it is desirable tat the force required to part the breaking link be equal to the tensile strength of the breaking link through a small rope angle with the vertical. This angle is illustrated as 0 in FIG. 1. Once the normal working range of this angle has been exceeded, however, it is desirable to arrange for parting of the breaking link by a substantially smaller horizontal component of force. Thus under normal operating conditions, the cou pling device is arranged to permit the guide cable an ample practical working range of from 0 to 10 to 15 degrees throughout which the tensile strength of the breaking link alone limits the maximum horizontal component of the cable pull. Once, however, the larger allowable angle of deviation from the vetrical is exceeded, then the coupling device will separate when a horizontal compoent of force of a much less magnitude occurs. This load-limiting fea ture is accomplished by the particular geometric relationships and portions of the component coupled parts.

FIG. 1A illustrates the forces acting on a coupling member. The upper portion 340 of the coupling member is connected to the top of a post 352 in a manner so as to allow universal motion between the upper portion and the post through a limited angle with the vertical. A breaking link L connects the member 340 to the top of the post 352. The strength of the breaking link is the load-limiting factor through an angle with the vertical. Thus the force P required to break the breaking link within angle 0 is equal to the breaking stress of the link L. When the angle of the guide line force P exceeds the limiting angle 0, the post top and the shoulder of member 340 meet, such as at A. The lever arm thus formed provides a load amplification on the breaking link L. The geometric relationship between the vertical dimension x of member 340 and the horizontal component 0 of the member 340 is selected so that the maximum horizontal component H required to separate link L is below a predetermined maximum allowable load. A preferred range of ratios of x to a is between 2 /2 to l and 8 to 1. Ratios of between about 5 /2 to l and 6 /2 to 1 have been found to be particularly useful.

As noted above, for rope angles ranging from the vertical to 0, the rope pull P is axial to link L. The angle 0 is chosen as a limiting angle to provide a permissible maximum horizontal component H for which the guide post can be safely designed to withstand. In a typical sitnation where the guide rope has a breaking strength of from 45,000 to 50,000 pounds, a breaking link L with a 33,000-pound ultimate load is suitable. A ten degree maximum value for 0 also is suitable under most operating conditions. With a breaking link L of 33,000 pounds, the post top value of horizontal force H can be adjusted by proportioning the x/ a ratio. The H component needed to fail link L is found from the relationship For example, with an x/ a ratio of 5.76, the H component needed to separate a 33,000 pound link is equal to 5,720. For an x/ a ratio of 6.6, the H component needed to break link L is 5,000 pounds.

Referring to FIGS. 2-5, a preferred embodiment of apparatus assembled in accordance with the present invention will now be described in detail. A coupling device, generally designated by the numeral 40, is used to connect a guide post, for example guide post 452, to a guide cable, for example guide cable 455. It is preferred that the coupling device 40 be disconnectably connected to the guide post 452. The coupling device 40 may then be removed in a conventional manner with the guide cable 455. However, the connection between the coupling device 40 and the top of the guide post 452 may take any convenient form. For example, as illustrated in FIG. 2, the upper portion of the guide post 452 is provided with a suitable annularly extending groove 460 having beveled shoulders 461 and 462. A member 470 of the coupling device is provided with suitable holes for locking dogs 463 which are mateable with the annular groove 460. A sliding sleeve 464 is provided with an annular recess 465 which is alignable with the locking dogs 463 to permit the locking dogs to retreat out of annular groove 460 and to thus disconnect the members. When the coupling device is in position on the post, the sliding sleeve is held in the engaged position so that the sleeve forces the locking dogs inward into the annular groove 460. The sleeve is normally maintained in this position by means of suitable springs 466. When it is desired to release the connection, a sinking bar (not shown) is placed over cable 455 and dropped onto the upper portion of the coupling device. The sinking bar is provided with suitable fingers for inserting through holes 106, 107, 108 and 109 in the upper cap member 105 to depress sleeve 464 and allow the locking dogs to retreat outward into the annular groove 465. The sinking bar is aligned in position on the coupling device by means of camming lugs 470, 471, 472 and 473. Thus as long as the force applied on the guide post by the guide line is in a vertical or near vertical direction, the coupling device of the present invention functions in a conventional manner.

As described above, the lower stationary portion of the coupling device functions in a known manner to disconnectably connect the guide line to the guide post. The present invention is particularly concerned with the lateral load-limiting means incorporated into the coupling device. Thus in accordance with the invention, the guide cable 455 is connected by suitable means to the upper end of a breaking link 120. For example, the guide cable 455 is conveniently connected to member 130 by means of fitting 131. The member 130 is connected in turn to an upper spherical member 132 which is positioned in a spherical recess in the upper cap member 105. The spherical member 132 has a downwardly extending portion 133 which has threads cut into its lower end. The upper spherical member 132 is held in position by means of a threaded insert 134.

A lower spherical member 140 is held in position in the lower portion of the coupling member 40 by threaded insert 141. The lower spherical member 140 has an upwardly extending sleeve 143 which slidingly engages over the downwardly extending portion 133 of the upper sperical member. The lower spherical member has a passageway through its center to accommodate breaking link 120. Thus the cupling member is made up of a lower stationary section and an upper movable section held together by a breaking link which may be sized in accordance with the requirements for a specific application. This assures that only axial forces can be applied to breaking link 120 so that it will fail under tension in a predictable manner.

FIG. 3 shows the position of the coupling device when the direction of pull of the guide cable exceeds an allowable angle with the vertical. The outer sleeve of the lower stationary portion of the coupling device has a shoulder 101 and a spherical guide bearing neck portion 102. The upper movable cap member 105 of the coupling device has a lower shoulder 206. When the direction of pull exceeds a predeterminable angle, the two corresponding shoulders 101 and 106 meet, as shown by the numeral 110 in FIG. 3, to establish a fulcrum point. By selecting the length of the lever arm and the ultimate strength of the breaking link, the maximum lateral pull H that can be exerted on the guide post by the guide cable can be adjusted to any desirable value.

After a rupture of the breaking link has occurred, the upper movable portion 105 of the coupling member is free to go with the guide cable 455. The lower stationary portion of the coupling device remains connected to the top of guide post 452. A stiff spring 113 and piston member 114 are provided beneath the lower spherical member to urge the spherical member into a position so that extension 143 returns to a vertical position. This is done to prevent fouling on the extension when subsequently coming back onto the guide post to remove the lower stationary portion of the coupling device so that a new coupling member and guide cable can be attached.

With reference to FIGS. 6 and 7, an alternative embodiment of apparatus assembled in accordance with the present invention will be described in detail. A coupling device, generally indicated by the numeral 70, is used to connect a guide cable 71 to a guide post 72. The connection between the lower stationary portion of the coupling member and the guide post is made in a conventionally known manner by means of a spring latch coupler, which coupler includes spring 73 and latch member 74 which slides in keyway 75. The spring latch member is connected and disconnected from the guide post utilizing known means.

The coupling device is made up of two major parts; the lower stationary portion and the upper movable portion. The stationary portion of the coupling device includes outer sleeve 76 and inner sleeve 77. A chamber for a spherical member is provided by means of housings 78 and 79 which are secured to the stationary portion by suitable connecting means. A breaking link 80 is connected between a pair of spherical members 81 and 82 by means of suitably overlapping telescopic sleeves 83 and 84.

The upper spherical member 82 is contained in a recess in upper cap member 85 and retained there by means of threaded insert 86. The upper cap member is connected to cable 71 by means of collar 87 having ball 88 which is captured on the upper cap member by means of fitting 89. The fit between upper cap member 85 and insert 78 of the stationary portion of the coupling device is such that the guide line is allowed free movement through a predetermined angle before the corresponding shoulders of the two pieces meet and form a pivot point. Thus as illustrated in phantom, the directional pull of the guide line may normally deviate somewhat from the vertical before bringing into play the leverage system which will reduce the amount of lateral force needed to part breaking link 80.

An additional feature of this embodiment of the invention is the provision of an outer tubular sleeve 90 which assists in preventing damage to or inadvertent tripping of the coupling device. A flexible rubber sleeve 91 is also provided around the corresponding shoulders of the upper cap member 85 and insert 78 to prevent foreign particles from becoming lodged in the opening between the shoulders and thus changing the leverage point.

With regard now to FIGS. 810, inclusive, another alternative embodiment of the present invention will now be described in detail. The lower stationary portion of the coupling device used to couplethe guide line to the guide post in this embodiment is generally similar to the lower portion of the coupling device used in the preferred embodiment illustrated in FIG. 2; and, for the sake of convenience, similar numbers will be used to describe similar parts of the embodiments. Thus the coupling device attaches to the top of a guide post 452 by means of locking dogs 463 contacting annular groove 460. An outer member 100 cooperates with an inner member 470 to form an annular chamber in which a sliding sleeve 464 may move. The sliding sleeve 464 engages with the rearward portion of the locking dogs and, depending on the position of the sleeve 464, either urges the dogs 463 into annular groove 460 or allows the dogs 463 to retreat out of the annular groove 460. Spring member 466 urges the sliding sleeve upwardly into a position which, as shown in FIG. 8, forces the locking dogs into a position which disconnectably connects the coupling device to the guide post.

The upper movable portion of the coupling device is connected to the lower portion by means of a universal joint formed of U-shaped members 501 and 502. One of the U-shaped members 501 is fixedly connected to the lower stationary portion while the other interlinked U- shaped member is arranged out of phase and fixedly connected to the upper movable portion of the coupling member. The guide cable 571 is connected to the upper movable portion by suitable means, such as collar 587, extension 590, breaking link insert 591 and cap member 592. In this particular embodiment, the breaking link is not an essential element to limit lateral force and is used only to limit the maximum force applied by the cable. In the event that an excessive force does cause breaking link 591 to part the movable portion of the coupling device which remains connected to the post is retained in an upright position by means of resilient member 530 acting on extension arm 531. Thus guide cable failure is avoided and so prevents the tangling of hundreds of feet of wire cable around the Christmas tree.

The upper movable portion of the coupling device is provided with downwardly projecting shoulders 550-554. One or more of these shoulders contact the upper end of sliding sleeve 464 when the direction of pull of guide cable 571 exceeds a predeterminable angle. If the angle increases, the shoulders depress sliding sleeve to a position where the locking dogs are cammed out of groove 460; and thus the guide line is released from the post.

Although specific embodiments of apparatus have been described, the invention is not limited to only these embodiments but is intended to include all embodiments within the scope of the appended claim.

What is claimed is:

1. The method of removing a guide line from a guide post located at an underwater well site from a floating vessel without damaging the guide line or the guide post comprising the steps of applying force on a guide line connected to a guide post, said force being from'a direction such that there is a lateral component of force which exceeds a predeterminable value and automatically releasing said guide line from said guide post in response to said lateral component of force.

References Cited UNITED STATES PATENTS 2,085,074 6/ 1937 Boyles. 2,889,168 6/1959 Engelhardt 294-83 3,050,139 8/1962 Hayes 7 3,163,228 12/1964 Hayes 166-5X 3,239,016 3/1966 Alexander 29-427X CHARLIE T. MOON, Primary Examiner US. Cl. X.R. 166-.5; l757 

